The role of robotsConstruction and destruction

ON EARTH, valuable assets are serviced, upgraded and recycled; they are also protected and, now and then, attacked. None of this is yet happening in space. But all of it could.

Some satellites break down; all of them, eventually, run out of fuel. Robotic service spacecraft that can identify a satellite, grab it and manipulate it could get around those problems. Orbital ATK, an aerospace company based in Virginia, has developed a spacecraft along these lines that works a bit like a mobility scooter; it provides somewhere with an engine for an elderly spacecraft to settle down in when it can no longer get around on its own. Orbital hopes to use such spacecraft to extend the lives of communications satellites that are out of fuel but still making money, and has signed a contract with Intelsat to this end.

An alternative to assisted mobility is refuelling. The Naval Research Laboratory, NASA and DARPA—the Pentagon’s advanced-technology arm—are all working on various projects for spacecraft that could refuel satellites and even repair them in orbit, using a range of tools and complex robotic arms.

A more radical approach is to use orbiting robots to make new spacecraft rather than service old ones. Tethers Unlimited, based in Washington state, is working on a “SpiderFab” that would combine robotic arms with a form of 3D printing to create structures much larger and more delicate than anything that can fit into the fairing of a launcher. Satellite-makers have become adept at folding up solar panels and antennae so as to fit a lot of spacecraft into those small spaces. But the complicated unfurlings, articulations and poppings-into-place required tend to increase both expense and risk, and make some approaches impossible.

Structures built with technologies such as the SpiderFab could change the way the communications-satellite industry works. Platforms with big solar panels and engines would take care of the housekeeping for a whole range of communications packages that could be smaller and launched more frequently, thus keeping the technology much more up-to-date and reducing risk.

All this might have an even bigger effect on science. Space is a great place for telescopes, but it is very difficult to get a big one up there. One reason why the James Webb Space Telescope that NASA and the European Space Agency are due to launch in 2018 has a budget of $8 billion is the need to fold a sunshield the size of a tennis court and a polished mirror 6.5 metres across into the 5.4-metre fairing of an Ariane 5. A combination of big structures and techniques that let a number of small mirrors spread over a large area do the work of a single much bigger mirror would allow remarkable new instruments to be built. Such instruments might be much better than those on the ground at observing, for example, the fascinating planets being discovered around other stars.

Another use for robots in space is asteroid mining. Some asteroids have orbits similar enough to the Earth’s to allow a spacecraft in orbit to get to them with a relatively small amount of fuel—much less than what is needed to get it into orbit in the first place. Like many other staples of science fiction, mining these flying boulders and mountains is now on the Silicon Valley startup agenda. The commodity of greatest interest is not a precious metal (though some of those are to be found on asteroids) but something that in space is much more valuable: water.

Human space travellers need water, as well as oxygen, which can be made from water. They, and their spacecraft, also need fuel: hydrogen made from water fits that bill. Once a certain amount of activity is taking place in orbit, especially if it involves a human presence, getting water from asteroids, in some of which it can be found either as ice or as hydrated minerals, could start to make more sense than hauling it up from Earth.

This will take time, but Deep Space Industries and another asteroid-mining startup, Planetary Resources, recently found a patient investor. Luxembourg knows a bit about space; two of the big four satellite operators, Intelsat and SES, in which its government is a shareholder, are based there. It is also well able to afford a flutter, and tightly knit enough to give a far-out idea with a few enthusiastic supporters a hearing. This summer Luxembourg announced that both companies would benefit from the €200m it will be spending on asteroid-mining initiatives.

What goes up must come down

Fuel from beyond could keep some satellites in orbit indefinitely. Others, though, need to be got rid of. In the lowest orbits—those of the ISS and below—the problem has a natural solution: drag in the outer reaches of the atmosphere will bring anything down in a matter of decades (the ISS has to be regularly boosted). But in other orbits space debris—consisting of dead satellites and their fragments, as well as the leftovers of discarded launchers—builds up. Even in the most debris-ridden orbits, between 700km and 900km, the risk of hitting something is pretty low; the chance of a close call is perhaps 1% per satellite-year, according to Brian Weeden of the Secure World Foundation, an American NGO. But satellites have been lost to such collisions; more satellites mean more such collisions; and collisions create yet more junk. Left to itself, the problem can only get worse. “It’s like climate change,” says Mr Weeden. “By the time it becomes a really big problem it may be too late to do anything about it.”

One answer is to make satellites more responsive and ensure that their operators are better informed. America’s armed forces use radar and telescopes to keep track of everything bigger than about 10cm across, and provide warnings when a bit of junk is going to come close to a functioning satellite. Analytic Graphics, a company that sells orbit-planning software, is moving towards offering a similar service that is better tailored to the needs of commercial-satellite operators. Like Earth-observation startups, but in reverse, it is using ever cheaper commercial technology to do what only governments did before. It is currently tracking about half as many objects as the US Air Force provides data on, but its capacities are fast increasing. It may soon offer its customers a better service.

The other answer is to clean things up—yet another job for robots. In 2017 an ESA spacecraft built by Surrey Satellite Technology, a pioneering smallsat company now owned by Airbus, will test its ability to ensnare a nearby cubesat in a net, reel it in and attach a “dragsail” to consign it to death by re-entry. It will also look at a technology for harpooning bits of junk. In the same year Astroscale, a Singapore-based startup, plans to launch a satellite to get a better measure of space junk. (Ground-based radar can see little that is less than 10cm across; the size of a cubesat was chosen in part because anything smaller would risk being invisible from Earth.) In 2018 Astroscale plans to try out a satellite with an adhesive patch to which any piece of junk can stick.

As it happens, very similar technologies might also be used for removing satellites that some people want in position and others do not. Anti-satellite (ASAT) weapons that target satellites have been developed by America, China and Russia, but if they were used it would be fairly obvious who the attacker was. A stealthy little satellite that could take them out from close by might work better; the victim might never know for sure if its satellite had been attacked or just broken down.

Here, too, better local information would help. America recently sent a pair of small satellites up to geostationary orbit to keep a much closer eye on both its own satellites and those of other countries. A second pair was launched on August 19th. But there are limits to this approach. As Doug Loverro, America’s Deputy Assistant Secretary of Defence for Space Policy, puts it, space is an environment which, at the moment, favours attack over defence.

Star wars writ small

That said, Mr Loverro identifies three ways of ensuring a continued satellite capability, all of which America is pursuing. One is active defence: measures that would make an ASAT attack more difficult. The second is resilience. Commercial service providers and America’s allies have more assets in space than ever before. The use of those capabilities, both on a routine basis—relying on commercial satellite links rather than bespoke military ones for many operations, for example—and as required in an emergency would make it harder for an adversary to deal a crippling blow with an ASAT strike. There would be just too many targets.

The third response is replenishment, which means having some back-up satellites safely on the ground, ready to be sent into space at very short notice. Another of DARPA’s space projects, XS-1, is challenging commercial teams to develop partially reusable launch systems that could get a couple of tonnes into orbit every day for ten days in a row. That could improve the economics of small satellites yet further, and allow the armed forces to feel much more certain of their ability to keep using space.

But there is another side to that use. Some systems designed to hit satellites might also be able to take out an intercontinental ballistic missile (ICBM) during the part of its trajectory when it is above the atmosphere. In the 1980s America’s “Star Wars” programme came up with the idea of so-called brilliant pebbles—thousands of small satellites that could spot and intercept rising ICBMs. The viability of such a system was hotly debated until the first Clinton administration pulled back from all space-based missile defences, on the argument that they would prove destabilising. That rendered the question moot.

The geopolitics of missile defence remain tricky. However, it is a sure bet that in a world where a smartphone has as much processing power as a Cray supercomputer had in the 1980s, and startups are launching satellites by the hundreds, a brilliant-pebble constellation is technologically a lot more plausible than it used to be, even though it might still prove politically unacceptable. Moreover, these capabilities, though at their most developed in America, are not unique to it. Warfare, both defensive and offensive, may yet prove to be an application where, as with communications, navigation and observation, space-based assets offer a regional or worldwide service that provides a distinct edge over surface-based alternatives.

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